How can I find the center of mass

How can I find center of mass of a frame? I need to find the speed of first and second frame with using center of mass and time. These are frames:

Answer 1

[Image Analyst]

Use regionprops():

props = regionprops(mask, grayImage, 'WeightedCentroid');
xCOM = props.WeightedCentroid(1)
yCOM = props.WeightedCentroid(2)

If you want the unweighted centroid (unweighted by the gray scale image's values), use 'Centroid' instead of 'WeightedCentroid'.

To get the speed, take the delta x and y and use sqrt() to find the distance between and then divide by the time difference between the frames

distance = sqrt(x2-x1)^2 + (y2-y1)^2);
speed = distance / deltaTime;

[Anil Cem ALMASULU]

calculating distance is okey but I couldn't find centers of mass I hane never seen there functions. Can you explain me how I can?

[Image Analyst]

Did it throw an error? regionprops() is in the Image Processing Toolbox and is one of the main functions of that toolbox. Type

>> ver

to see if you have that toolbox.

[Anil Cem ALMASULU]

I could not set up Image Processing Toolbox .I mean ı dont know how to set up Image Processing Toolbox and how to run. When I write your code I get "Unrecognized function or variable 'mask'." error.Like that